1. Field of the Invention
The present invention relates to an image display device and a projection-type image display apparatus.
2. Related Background Art
FIG. 10 shows a three-panel transmission-type liquid crystal display device. When using such a three-panel transmission-type display device, parallel light beams separated in three primary colors of R (red), G (green) and B (blue) perpendicularly enter into microlens elements provided on three faces of a dichroic prism to form light spots on the surface of a barrier element having liquid crystal shutters arranged on the focal position of the microlens elements, and each color light transmitted by the liquid crystal shutters for controlling the transmitted light amount corresponding to the position of the light spots is reflected or transmitted by the dichroic prism and emitted from the remaining face of the dichroic prism. The images of the respective colors are superposed by the dichroic prism, and an image is displayed on a screen by a projection lens focused on the aforementioned microlens element surfaces.
In FIG. 10, the projection lens is positioned between the screen and the dichroic prism and is focused on the surface of the microlenses.
FIG. 11 shows a single-panel transmission-type liquid crystal display device. When using such a single-panel transmission-type liquid crystal display device, parallel light beams separated into three primary colors of R (red), G (green) and B (blue) are introduced with respective angles into a microlens element to form light spots in three different positions on the surface of a barrier element having a liquid crystal shutter on the focal position of the microlens element, and the lights of the primary colors transmitted by the liquid crystal shutters in three positions for controlling the transmitted light amount corresponding to the positions of the light spots arc projected on a screen by a projection lens focused on the aforementioned microlens element surfaces to perform image display.
In FIG. 11, the projection lens is positioned between the screen and the barrier element and is focused on the surface of the microlenses.
FIG. 12 shows a single-panel reflection-type liquid crystal display device. Parallel light beams of three primary colors of R, G, B are introduced with respective angles into the adjacent microlenses to form light spots of the microlenses on liquid crystal shutters for respective colors provided on a reflective substrate, and such spots reflect lights as new light-emitting points through the microlenses to display an image on a screen by a projection lens focused on the surface of the microlens element. In such a case, one of the R, G and B lights may be introduced, reflected and emitted perpendicularly to the microlenses. In the reflection-type display device, since each light beam is reflected in the direction of the incident light, a polarizing beam splitter must be employed in order to separate the entering light and the reflected light. Also, since the microlenses are arranged on the plane of a single panel, the boundary of each microlens has to be hexagonal or rectangular, and the hexagonal microlenses can only handle four colors at maximum including the case of perpendicular entry, while the rectangular microlenses can only handle six colors at maximum.
In FIG. 12, the projection lens is positioned between the screen and the polarizing beam splitter and is focused on the surface of the microlenses.
In such a single-panel-type configuration, it is required to form R, G and B pixels and liquid crystal shutters for controlling the brightness of the pixels while corresponding to each microlens. Consequently, complex wiring and complex correction of optical path length corresponding to the refractive index depending on the wavelength or the like is involved. More specifically, since R, G and B pixels are arranged in a mixed manner on a panel, the wiring connecting such pixels becomes complex. It is also required to form color filters constituting the R, G and B pixels in a mixed manner on the panel. Also such filters have to be formed with different thicknesses for different colors because of the difference in the refractive index depending on the wavelength.
In consideration of the foregoing, the present invention provides a transmission- or reflection-type image display device having the advantages of the three-panel configuration and the conventional single-panel configuration and a projection display apparatus utilizing such an image display device.
Also the present invention provides an image display device capable of easily realizing multicolor display with the single panel or stereo display method and a projection display apparatus utilizing such a device.
The present invention enables reflection- or transmission-type display capable of achieving color synthesis without a dichroic prism or a polarizing beam splitter.
In a system utilizing a dichroic prism or a polarizing beam splitter, the multicolor liquid crystal display can only be achieved with a plurality of polarizing beam splitters or a dichroic prism. As the prism has 6 faces one of which is used for emitting the synthesized colored light, the remaining 5 faces can be used for the primary R, G, B colors and two other colors. In this case, however, there are required a plurality of panels.
In the single-panel reflection-type configuration, since the primary colors have to be introduced at different angles, there can be utilized 3 primary colors when using rectangular microprisms or 4 primary colors when using hexagonal microprisms.
According to the present invention, therefore, there is provided an image display device comprising a microlens element having microlenses arranged in a two-dimensional matrix; illumination means having a group of small light-emitting points positioned at a predetermined distance respectively corresponding to the microlenses and arranged in a two-dimensional matrix; and a barrier element having shutters positioned between the microlens elements and the illumination means or at the side of the surface of the microlens element and adapted to control the light amount transmitted by the respective microlenses; wherein each optical axis connecting the microlens and the small light-emitting point is inclined to the normal line to the surface of the image display device over the entire image display device; and an image display consisting of a group of real images or false images of the small light-emitting points is formed in an infinite distance or in a position separated by a predetermined distance from the image display device and displaced laterally by a predetermined amount.
According to the present invention, there is also provided an image display device comprising a microlens element having microlenses arranged in a two-dimensional matrix; illumination means of a parallel beam for illuminating the microlens element from the rear side thereof; and a barrier element having shutters positioned between the microlens elements and the illumination means or at the surface at the light-emitting side of the microlens element and adapted to control the light amount transmitted by the respective microlenses; wherein each optical axis connecting the microlens and the small light-emitting point is inclined to the normal line to the surface of the image display device over the entire image display device; and an image display consisting of a group of real images or false images of the small light-emitting points is formed in an infinite distance or in a position separated by a predetermined distance from the image display device and laterally displaced in parallel manner by a predetermined amount therefrom.